The present invention relates to frames for highway crash attenuators such as truck mounted attenuators.
June U.S. Pat. No. 5,642,792 and Leonhardt U.S. Pat. No. 6,092,959 disclose highway crash cushions intended to be mounted on a shadow vehicle such as a truck. In both cases, the disclosed crash cushions include frames having transverse elements interconnected by side elements. The side elements are articulated such that they can fold outwardly to allow the frame to collapse in an impact. Premature collapse of the frame is prevented by restraints coupled to the side elements. In the June patent, these restraints include diagonally oriented cables extending between the center portions of the side elements and one of the transverse elements. These cables prevent the side elements from moving outwardly until they are released by rotation of pins that secure the cables to the transverse element. In the Leonhardt patent, the restraints take the form of bolts secured between adjacent central portions of the side elements, on either side of the respective central hinges. The central hinges of the side elements are prevented from opening until after the bolts have been broken during an impact.
Though effective in operation, the diagonal cables of the June patent may not be optimal for applications that do not use a probe to initiate collapse of the frame. Because the bolts used to hold the frame of the Leonhardt patent in the original position are each responsive only to forces at the respective central hinge, the opening of the hinges on opposed sides of the frame are not coordinated with one another.
Gertz U.S. Pat. No. 5,248,129 describes another frame that includes a scissors linkage that is held in an initial position by cables that extend between bars positioned across the frame at the upper and lower hinges of the linkage. The Gertz patent relates to a different type of linkage in which rigid bars cross between the top and the bottom of the frame to form the scissors linkage.
By way of general introduction, the highway crash attenuator frame described below includes one or more tension elements secured between opposed side elements near the respective central hinges. Each tension element extends across the longitudinal axis of the frame, from one side of the frame to the other side of the frame. Each tension element includes a mechanical fuse that fails in tension when the first and second side elements of the frame apply an excessive load to the tension element. Once the mechanical fuse fails, central hinges on both sides of the frame are simultaneously allowed to begin opening. In this way, the collapse of the frame is coordinated between the left and right sides of the frame.
The foregoing paragraphs have been intended by way of general introduction, and they are not intended to narrow the scope of the following claims in any way.